Many factors can affect the prevalence of AGN activities.
One important question is how to bring the gas down to
the galaxy center to fuel the supermassive black holes (SMBH).
In the literature, two kinds of mechanisms are proposed.
One is the internal secular evolution process. The torque
induced by non-axisymmetric galactic structures can
drive slow and significant inflow [1]}, [2]}, [3]}, [4]}.
The galactic bar is one of the most prominent
non-axisymmetric structures, and exists in about 40% of
spiral galaxies [5]}. And there is evidence
showing that bars can enhance star formation in the central
regions of galaxies [5]}, [7]}. However,
whether galactic bars can significantly affect AGN
activity is still under debate
[8]}, [9]}, [5]}, [11]}, [12]}, [13]}.
